SERUM SEX-HORMONE BINDING GLOBULIN, CARDIOVASCULAR RISK-FACTORS, AND ADRENAL CORTISOL RESPONSES TO DEXAMETHASONE AND CORTICOTROPIN

Basal cortisol levels and cortisol responses to dexamethasone (DXM) and corticotropin were studied in relation to serum levels of sex hormone-binding globulin (SHBG), testosterone (T), free T, estradiol (E2), insulin-like growth factor I (IGF-I), high-density lipoprotein cholesterol (HDLC), triglycerides (TG), and insulin in 30 men. SHBG was positively correlated to age (P < .01), HDLC (P < .05), and total T (P < .05) and negatively correlated to TG (P < .02) and insulin (P < .001). SHBG was inversely related to corticosteroid-binding globulin (P < .05), but was not significantly associated with IGF-I. Free T was positively related to TG (P < .05), insulin (P < .01), total T (P < .001), and basal (P < .01) and free cortisol (P < .05). Corticotropin-stimulated cortisol responses were negatively associated with SHBG (P < .001) and positively associated with insulin (P < .01). Multiple linear regression analyses with SHBG as the dependent variable indicated that cortisol response alone explained 34.0% and together with age 46.2% of the variation of SHBG levels. Only insulin and age, but not cortisol response, remained significant predictors of SHBG concentrations when entered simultaneously into the mathematical model; this model explained 55.1% of the variation of SHBG levels. Thus, in addition to insulin and age, cortisol reserves and secretion seem to have significant associations with serum SHBG and free T concentrations. © 1993.